I am trying to install gentoo onto my PowerBook G4 (5,9–A1139). However, whenever I attempt to boot from the installation disc (which I burned the Gentoo ppc minimal installation cd iso onto, and am installing with the ppc32 nol3 command), there are errors stating that the "hwsetup failed to start", "unmute needs service(s) alsasound", "cannot start gpm-pre as hwsetup would not start", and then farther down, "cannot start autoconfig as hwsetup would not start". Why is this happening and what can I do to fix it? Thank you in advance for your help.

Minimal gentoo cd is always problematic. it's minimal. You should use something else!

Please try another live-cd which does not name minimal in its name. Not sure if sysrescue-cd or something similar exits for apple hardware!

There is no real requirement to use a gentoo disc to install gentoo, you just need a linux live-cd / live-usb for the "correct" architecture which boots and works, and has the tools in questions on board